Prostate cancer is a leading cause of male mortality. Approximately 30,000 deaths per year can be traced to this cause in the United States alone. Consequently, various methods of detecting such cancers have been developed which include palpation through rectal examinations, a prostate specific antigen blood test and examination using a combination of various electronic devices and direct physical contact with the organ. However, each of these methods suffers from some type of shortcoming.
Palpation through digital rectal examination is the simplest, most inexpensive and fastest method of detection. Unfortunately, it is also the least reliable or accurate. It relies on the subjective judgment and experience of the examiner and cannot, in any event, accurately indicate the location or size of a tumor. Furthermore, by its reliance solely on the examiner's sense of touch, by definition it cannot detect deeply embedded or particularly small growths. It therefore fails as an effective early warning indicator.
These difficulties led to the development of various prostate examination devices incorporating electronic or electrically-driven components. For example, various patents disclose the use of ultrasound devices designed for placement on fingertips to be used in conjunction with digital rectal exams. Typical of these are the patents to Hansoka, et al. (U.S. Pat. No. 5,284,147) and Wedel, et al. (U.S. Pat. No. 5,088,500). This type of fingertip ultrasound examination has become popular in many other areas of medicine as disclosed in the patent to Peszynski (U.S. Pat. No. 5,598,846) where a fingertip ultrasound transducer is provided for viewing internal body parts during surgery. But one or more of the following problems are inherent with these devices. Either they are relatively costly, their use and interpretation of their results require a high level of examiner skill or the time necessary for the examination procedure is excessively long thereby further raising the cost of use.
Another examination tool routinely used in conjunction with digital rectal examinations is the prostate specific antigen blood test (PSA). However, studies have shown that this blood test provides an undesirably high level of both inaccurate positive readings (up to 25%) and inaccurate negative readings (up to 30%). As a result, some men who do not need treatment are subjected to needless invasive medical procedures while others remain uninformed of their true condition. It has been found that the number of false positive and negative readings from the PSA test can be significantly reduced if the prostate specific blood antigen reading is divided by the volume of the prostate. To this end, the patent to Zirps et al. (U.S. Pat. No. 5,423,332) discloses a fingertip probe which includes a device for automatically and operator-independently determining in vivo the mass of the prostate gland. Although this device represents a significant advancement of the art in this field, it still requires the use of relatively costly and complex transducer and monitoring equipment.
In the 1950's, it was discovered that the surface temperature of skin in the area of a malignant tumor exhibited a higher temperature than that expected were no disease present. Thus, by measuring body skin temperatures, it became possible to screen for the existence of abnormal body activity such as cancerous tumor growth. With the development of liquid crystals and methods of forming temperature responsive chemical substrates, contact thermometry became a reality along with its use in medical applications. Devices employing contact thermometry could sense and display temperature changes through indicators which changed colors, either permanently or temporarily, when placed in direct physical contact with a surface such as skin, reflecting a temperature at or near the point of contact. An abnormal reading would alert a user to the need for closer, more detailed examination of the region in question. However, the art in this area has been directed primarily at sensing and displaying temperatures on exterior skin surfaces. Thus, for example, the patent to Vanzetti et al. (U.S. Pat. No. 3,830,224) disclosed the placement of temperature responsive, color changing liquid crystals at various points in a brassiere for the purpose of detecting the existence of breast cancer, while the patent to Sagi (U.S. Re. 32,000) disclosed the use of radially arranged rows of temperature responsive indicators deposited on a disc for insertion into the breast-receiving cups of a brassiere for the same purpose.
There has been a failure to recognize that the same principle may apply to internal body organs. An abnormally high temperature at the surface of an internal organ when compared with surrounding tissue also indicates the likelihood of a medical problem. However, with regard to the prostate, the prior art has concentrated not on internal organ temperature measurement as a screening tool but rather on monitoring prostate temperature during hyperthermic prostate gland treatments after a problem has been found to exist. The patent to Cathaud et al. (U.S. Pat. No. 5,404,881) discloses one type of rectal probe used for this purpose, while the patent to Tihon et al. (U.S. Pat. No. 5,335,669) discloses another.
The applicability of contact thermometry to internal organ diagnosis has gone unrecognized. The prior art does not evidence an understanding of the advantages of diagnostic measurement of temperature in the prostate region as an early indicator of abnormalities. Furthermore, none of the prior art devices used in prostate examination provide a simultaneously simple, speedy, accurate and cost-effective solution to the prostate screening procedure.